The present invention relates to an automatic transmission system for a vehicle.
A shift lever of an automatic transmission system for a vehicle is provided with a shift lock mechanism for preventing a displacement of shift lever until an ignition switch is again turned on when parking range (P range position) is selected by a driver through the shift lever under a condition that the ignition switch is turned off.
Japanese Patent Provisional Publication No. (Heisei) 5-322031 discloses a shift-by-wire type automatic transmission system wherein an operation of a shift lever is converted into an electric signal. A manual valve and a parking mechanism of an automatic transmission are controlled by an electrically operated actuator according to the electric signal to change of an operation range of an automatic transmission.
However, such a shift-by-wire type automatic transmission system is further required to improve utility in combination with a common shift lock mechanism.
It is therefore an object of the present invention to prove a shift-by-wire type automatic transmission system which preferably controls the operation of a range selector such as a shift lever so as to prevent a discord between an operation range selected by the range selector and an actual operation range selected in an automatic transmission.
An aspect of the present invention resides in an automatic transmission system which is for a vehicle and comprises an automatic transmission, a range selector, a shift-by-wire system and a lock mechanism. The automatic transmission selectively takes a plurality of operation ranges. The range selector is operated by a driver of the vehicle to select one of command operation ranges. The shift-by-wire system converts the selected command operation range into an electric signal and changes an actual operation range of the automatic transmission into the selected command operation range by driving an actuator according to the electric signal. The lock mechanism restricts the operation of the range selector when the shift-by-wire mechanism is electrically turned off.
Another aspect of the present invention resides in a method of controlling an automatic transmission system for a vehicle, the automatic transmission comprising an automatic transmission which selectively takes a plurality of operation ranges, a range selector which is operated by a driver of the vehicle to select one of command operation ranges and a shift-by-wire system which converts the selected command operation range into an electric signal and changes an actual operation range of the automatic transmission into the selected command operation range by driving an actuator according to the electric signal, the method comprising restricting the operation of the range selector when the shift-by-wire mechanism is electrically turned off.
The other objects and features of this invention will become understood from the following description with reference to the accompanying drawings.